| abstract |
Provided are a structure and a method for making the same, said structure being capable of suppressing the bow of a board on which a CMUT has been formed without affecting a film arrangement that has been optimized so as to maintain the characteristics of the CMUT and further suppress the distortion of a membrane. A board bow prevention structure is provided to an area or position other than the area or position of a membrane that determines CMUT characteristics. For example, a bow prevention layer for preventing the board bow is formed, as the bow prevention structure, between the board and a first conductive film in the CMUT having a structure in which a first conductive layer and a second conductive layer are formed, on the board, with a cavity therebetween. If an insulating film located between the cavity and the first conductive film as well as another insulating film located between the cavity and a second conductive film are silicon oxide films, the bow prevention layer includes a silicon nitride film. |